Semiconductor device formation is commonly conducted in substrate processing systems or platforms containing multiple chambers, which may also be referred to as cluster tools. In some instances, the purpose of a multi-chamber processing platform or cluster tool is to perform two or more processes on a substrate sequentially in a controlled environment. In other instances, however, a multiple chamber processing platform may only perform a single processing step on substrates. The additional chambers can be employed to maximize the rate at which substrates are processed. In the latter case, the process performed on substrates is typically a batch process, wherein a relatively large number of substrates, e.g. 25 or 50, are processed in a given chamber simultaneously. Batch processing is especially beneficial for processes that are too time-consuming to be performed on individual substrates in an economically viable manner, such as for atomic layer deposition (ALD) processes and some chemical vapor deposition (CVD) processes.
Many high temperature CVD/ALD chambers have smaller single wafer carriers which provide known film uniformity upon deposition. Providing thermal and film uniformity in a large carousel-type batch processing chamber which uses a multi-wafer carousel susceptor rotating about a center pedestal driven by a dual-axis motor is more challenging because the wafers are off-axis relative to the rotation of the susceptor. Thermal and film thickness maps indicate the presence of hot spot handles (arcs) at 4 and 8 o'clock positions an cold spots at other places around the wafer edge. Accordingly, there is a need in the art for improved apparatus and methods to deposit uniform films in batch processing chambers.